The invention relates to a flange fitting for a pipe.
Pipes with integral flanges are frequently used to allow two adjacent pipes to be joined together end-to-end by fastening their respective flanges, for example by fastening bolts. However, it may be desirable or necessary to fit a flange to a pipe having no integral flange.
It is known to join a separate flange ring to a pipe. This may be done by welding. An alternative method is to locate a flange ring around a pipe before fitting a retaining ring in a groove formed towards an end of the pipe, thereby forming a flange fitting. The retaining ring radially projects from the pipe and therefore prevents axial movement of the flange ring beyond the retaining ring. When the flange ring is coupled with a corresponding flange, its axial position is limited by the retaining ring.
In such an arrangement, the retaining ring must be located radially inward of the bolt holes in the flange ring. The dimensions of a flange ring and the positions of the bolt holes are typically set according to a common standard or to correspond to an opposing flange. Consequently, the pitch radius of the bolt holes (i.e. the radius of the circle on which the bolt holes lie) and their diameter typically determines the size of the radially inward space available for accommodating a retaining ring. Where this space is limited, the size of a corresponding retaining ring may be limited to the extent that the structural integrity of the respective flange fitting would be compromised. In such circumstances, it may be necessary to weld the flange ring directly onto the pipe to form a permanent connection.
For these and other reasons, improved systems and methods are desired, including an improved flange fitting.